help please-ticking noise behind A/C - Heater panel

[omodos]

I bought a 3.0d 2004/54 today, I love it, BUT sat in the car whilst the ignition was off and shut the doors and I can hear a ticking noise coming from behind the A/C - heater controls panel, thing is it had been off for a good few hours before, about 4-5 hours. I just cannot make it go away, turned off and on air con, etc etc, should I take to a garage?is it a known issue? Please help, I am really anxious to find out what it could be and will have sleepless nights till I do.

thanks